The development of reliable methods for rapidly and simply measuring analytes in complex samples has become increasingly important. For example, the point of care testing in hospital emergency departments requires unskilled technicians to perform complex chemical and immunochemical assays to rapidly define the status of patients. The testing is usually performed by a nurse or an emergency room technician who are not trained as clinical chemists. The current practice of sending blood samples to the hospital laboratory is not feasible when the results are required within 30 min. The problem is thus that assay results are needed in a rapid time but the testing protocols, personnel and equipment available to the hospital emergency department are not compatible with this need. Other scenarios for obtaining rapid results through simple methods are in physicians offices, in patient homes and in field testing of pollutants and contaminants.
There is thus an unmet need for an immunoassay system that is simple, rapid and reliable.
Reliability in an immunoassay system is critical for the accurate measurement of the analyte. In an emergency room setting, the assay results can guide the physician in diagnosing and treating the patient. In a home setting, the assay result can, for example, help determine the amount and frequency of a therapeutic drug. In the field testing of pollutants and contaminants, the testing can define the extent of renovation or ground excavation needed to remove the contaminant.
Previous references regarding assay controls have not clearly defined parameters that require evaluation in assay devices. For instance, many publications simply provide examples of controls that determine the effect of non-specific binding. Some of these publications relate mainly to methods of controlling for non-specific binding and some references relate to devices that incorporate controls for non-specific binding. See, e.g., U.S. Pat. Nos. 4,533,629, 4,540,659, 4,843,000, 4,849,338, 5,342,759, 4,649,121, 4,558,013, 4,541,987, 4,472,353, and 4,099,886.